示例：通过本地文件导入导出数据

在使用JAVA语言基于openGauss进行二次开发时，可以使用CopyManager接口，通过流方式，将数据库中的数据导出到本地文件或者将本地文件导入数据库中，文件格式支持CSV、TEXT等格式。

样例程序如下，执行时需要加载openGauss jdbc驱动。

1. import java.sql.Connection;
2. import java.sql.DriverManager;
3. import java.io.IOException;
4. import java.io.FileInputStream;
5. import java.io.FileOutputStream;
6. import java.sql.SQLException;
7. import org.postgresql.copy.CopyManager;
8. import org.postgresql.core.BaseConnection;

10. public class Copy{

12. public static void main(String[] args)
13. {
14. String urls = new String("jdbc:postgresql://10.180.155.74:8000/postgres"); //数据库URL
15. String username = new String("jack");            //用户名
16. String password = new String("xxxxxxxxx");             //密码
17. String tablename = new String("migration_table"); //定义表信息
18. String tablename1 = new String("migration_table_1"); //定义表信息
19. String driver = "org.postgresql.Driver";
20. Connection conn = null;

22. try {
23. Class.forName(driver);
24. conn = DriverManager.getConnection(urls, username, password);
25. } catch (ClassNotFoundException e) {
26. e.printStackTrace(System.out);
27. } catch (SQLException e) {
28. e.printStackTrace(System.out);
29. }

31. // 将SELECT * FROM migration_table查询结果导出到本地文件d:/data.txt
32. try {
33. copyToFile(conn, "d:/data.txt", "(SELECT * FROM migration_table)");
34. } catch (SQLException e) {
35. k
36. e.printStackTrace();
37. } catch (IOException e) {

39. e.printStackTrace();
40. }
41. //将d:/data.txt中的数据导入到migration_table_1中。
42. try {
43. copyFromFile(conn, "d:/data.txt", tablename1);
44. } catch (SQLException e) {
45. e.printStackTrace();
46. } catch (IOException e) {

48. e.printStackTrace();
49. }

51. // 将migration_table_1中的数据导出到本地文件d:/data1.txt
52. try {
53. copyToFile(conn, "d:/data1.txt", tablename1);
54. } catch (SQLException e) {

56. e.printStackTrace();
57. } catch (IOException e) {

60. e.printStackTrace();
61. }
62. }
63. // 使用copyIn把数据从文件中导入数据库，
64. public static void copyFromFile(Connection connection, String filePath, String tableName)
65. throws SQLException, IOException {

67. FileInputStream fileInputStream = null;

69. try {
70. CopyManager copyManager = new CopyManager((BaseConnection)connection);
71. fileInputStream = new FileInputStream(filePath);
72. copyManager.copyIn("COPY " + tableName + " FROM STDIN", fileInputStream);
73. } finally {
74. if (fileInputStream != null) {
75. try {
76. fileInputStream.close();
77. } catch (IOException e) {
78. e.printStackTrace();
79. }
80. }
81. }
82. }

84. // 使用copyOut把数据从数据库中导出到文件中
85. public static void copyToFile(Connection connection, String filePath, String tableOrQuery)
86. throws SQLException, IOException {

88. FileOutputStream fileOutputStream = null;

90. try {
91. CopyManager copyManager = new CopyManager((BaseConnection)connection);
92. fileOutputStream = new FileOutputStream(filePath);
93. copyManager.copyOut("COPY " + tableOrQuery + " TO STDOUT", fileOutputStream);
94. } finally {
95. if (fileOutputStream != null) {
96. try {
97. fileOutputStream.close();
98. } catch (IOException e) {
99. e.printStackTrace();
100. }
101. }
102. }
103. }
104. }